The preparation of poly(ary ether ketones) by Friedel-Crafts polymerization techniques is well known in the art. For example, U.S. Pat. No. 3,065,205 describes the preparation of aromatic polyketones by Friedel-Crafts polymerization techniques using an organic solvent for the reaction. The solvents used are nitrobenzene, symmetrical tetrachloroethane, dichlorobenzene or carbon disulfide. Nitrobenzene is used as a solvent in all of the examples. The reaction mixture is stated as remaining homogeneous throughout the polymerization. However, the process described in U.S. Pat. No. 3,065,205 produces polymers of very low molecular weights and inherent viscosities ranging from 0.13 to 0.18, as measured in concentrated sulfuric acid.
In describing the difficulty in preparing polyketones such as those described in U.S. Pat. Nos. 3,065,205, 3,791,890 states the problem as the relatively intractable nature of the initial polymer-catalyst complex upon formation. The patent states the following in column 1, lines 10 to 20:
"Previous attempts to deal with the generally intractable state of the reaction product have included polymerizing the monomers in the presence of a soluble solid material to permit removing the product from the reaction medium and subsequently separating the soluble material by leaching. However, none of these prior techniques has proved entirely satisfactory." PA1 (i) at least one electrophilic aromatic diacyl halide of the formula EQU YOC--Ar--COY PA1 where --Ar-- is a divalent aromatic radical such as phenylene, diphenylether-4,4'-diyl, diphenyl-4,4'-diyl, naphthalene-diyl, and the like, Y is halogen such as chlorine, bromine or iodine with chlorine being preferred, and COY is an aromatically bound acyl halide group, which diacyl halide is polymerizable with at least one aromatic compound of (a)(ii), and PA1 (ii) at least one aromatic nucleophilic compound of the formula EQU H--Ar'--H PA1 where --Ar'-- is a divalent aromatic radical such as diphenylether-4,4'-diyl, 2,7-dibenzofuranediyl, diphenyl-4,4'-diyl, diphenylmethane-4,4'-diyl, naphthalene-diyl, phenanthrenediyl, and the like, and H is an aromatically bound hydrogen atom, which compound is polymerizable with at least one diacyl halide of (a)(i), and PA1 z is halogen, alkyl or alkoxy
In U.S. Pat. No. 3,791,890, an improved process is described in which polyketones are prepared in granular form in a two step process. In the first step diphenyl ether and at least one of terephthalic or isophthalic acid chlorides are reacted in the presence of o-dichlorobenzene, sym-tetrachloroethane, or dichloroethane as a solvent utilizing a Friedel-Crafts catalyst, such as aluminum chloride, at a temperature of from -15.degree. C. to 0.degree. C. All the examples use o-dichlorobenzene as the solvent. The patent states that an initial low reaction temperature is desirable to maintain control over the rate of reaction so that coagulation of the formed polyketone does not occur before dispersion can be effected. In the next step, the reaction mixture produced is dispersed into a fluid medium maintained at a temperature of at least 50.degree. C. The fluid medium is described as any gas or liquid in which the polyketone formed is substatially unreactive at the temperature employed in the process. The dispersion into a heated fluid is stated to segregate the particles of polymer that are beginning to form in the initial reaction mixture and prevent the agglomeration of the particles into a gelatinous mass. A granular polyketone is thus recovered. However, in this patent no viscosities for the polyketone are reported.
In U.S. Pat. No. 3,668,057 describes the preparation of copolyketones with reduced viscositites of about 0.9 dl/g (as measured in concentrated sulfuric acid at 25.degree. C.) under Freidel-Crafts polymerization conditions with o-dichlorobenzene as solvent. However, polymers with reduced viscosities of about 0.9 dl/g are boardline with regard to toughness in same end-use applications. Copolyketones with high reduced viscosities are possible using hydrofluoric acid as the solvent and boron trifluoride as the catalyst. However, due to the toxicity of hydrofluoric acid/boron trifluoride it is not a system which is conducive to commercialization.